1. Field of the Invention
The present invention relates to electronic braking systems for road vehicles and is concerned with a means of testing the operation of such systems with the vehicle static or substantially static.
2. Description of the Related Art
An electronic braking system (EPB) having compensation for the major disturbance to braking has been described in EP-A-0205277. In the latter system, the level of braking at each axle of a vehicle is made to be proportional to driver braking demand as signified by an electrical signal from a brake pedal and also proportional to axle load as assessed from axle load sensors. Alternatively, for some vehicles which have only small changes in load on particular axles, the operational load value is programmed into the system at final build or it is calculated from other measured axles, for example in the case where a towing vehicle carries a semi-trailer. In the latter case, the front axle load is substantially constant except in so far as a small percentage of the rear axle load increase is passed on to the front axle as a result of the trailer load being applied at some predetermined distance in front of the towing vehicle rear axle.
In all the latter cases, it is assumed that the axle loads are known to the system, and it would be an advantage (and possibly a practical requirement) that the resulting load-sensitive braking distribution should be able to be checked independently from time to time as a service check for test authorities or simply for maintenance purposes.